Yep, it's affecting everyone and as you found out talking to Customer Services, eBay are aware, trying to fix the issue, but no date for a fix yet announced.
They have issued a workaround that is, for a buyer to buy all the items, then the seller makes a partial refund of the excess postage.
Not ideal I know, but saves losing a sale.
Sellers have also mentioned they have a Note on their listings, informing buyers if they wish to buy more than ** items to let them know and the items will then be listed on one listing to effect one postage charge.
@robscurios
